Reddit user frankzapra shares that hot liquids can sometimes leak from your paper coffee cup when the drinking hole in the lid is lined up with the cup seam. To avoid this, just twist the lid a few degrees so that any drops of liquid that get in the seam won't break escape your cup.

It seems also that baristas like to lid cups this way as a bit of revenge on annoying customers, so if you routinely find your latte being served this way you may want to rethink your small talk strategy with your regular barista.